Explaining modal noise in optical communication

Question

Answer the following questions.

Question 1) Which is the most commonly used wavelength of light used for optical communication? Briefly describe why.

Question 2) Draw the variation of optical power with time for the digital NRZ bit stream '010111101110' by assuming a bit rate of 2 Gb/s. Compute the duration of the shortest and widest optical pulse.

Question 3) Write down the techniques used to handle polarization mode dispersion?

Question 4) Why does splicing of fiber cause optical loss?

Question 5) Briefly explain the significance of extinction ratio kept for digital modulation over laser diode.

Question 6) What are the problems in laser structures for the operation at higher wavelength region?

Question 7) Write down the advantages and disadvantage of APD (Avalanche Photodiodes) based optical receivers.

Question 8) The carrier velocity in a silicon p-i-n photodiode with 25 μm depletion layer width is 3x10⁴ m/s. Find out the maximum response time for the device.

Question 9) Describe briefly modal noise in optical communication.

Question 10) What do you mean by dry fiber use for WDM?